Geochemical imprints of occurrence, vertical distribution and sources of aliphatic hydrocarbons, aliphatic ketones, hopanes and steranes in sediment cores from ten Iranian Coral Islands, Persian Gulf

The levels, vertical distribution and sources of hydrocarbons and petroleum biomarkers were estimated for the first time in sediment cores (0–40 cm) from ten coral Islands of the Persian Gulf, Iran. Discrepant hydrocarbons, including linear n-alkanes (n-C11 to n-C40) and isoprenoids (AHs), aliphatic ketones (AKs), hopanes and steranes were measured in all core samples, showing mean concentrations ranging from 209 to 5388 μg g−1dw (∑30AH), 2–244 μg g−1-dw (∑13AK), 189–3713 ng g−1dw (∑31hopane) and 42–3864 ng g−1dw (∑15sterane), respectively. All sediment cores were found to be petroleum polluted, with ∑30AH > ∑31hopane > ∑15sterane > ∑13AK, with higher levels recorded at 10–20 cm, mainly at industrial sites. Various diagnostic indices revealed that hydrocarbons derived mainly from anthropogenic inputs, with significant contribution of biogenic origin at sites less polluted. Moreover, total organic carbon (0.24–23.45 mg g−1-dw), terrestrial and marine organic matter had an overwhelming effect on hydrocarbons deposition in sediment cores. Overall, findings provide relevant information for monitoring and preventing petroleum pollution in the sensitive ecosystems of the Persian Gulf.